#include <QtCore/QCoreApplication>

#include <QFile>
#include <QDataStream>
#include <QDebug>
#include <QImage>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QString fileName("fraktle3.gbr");

    // ------------------------------------------------

    QFile file(fileName);
    file.open(QIODevice::ReadOnly);

    quint32 headerSize;
    quint32 version;
    quint32 width;
    quint32 height;
    quint32 colorDepth;
    quint32 magic;
    quint32 spacing;
    QString brushName;
    char*   data;

    QDataStream in(&file);
    in >> headerSize
            >> version
            >> width
            >> height
            >> colorDepth
            >> magic
            >> spacing;

    if ((magic != 0x47494D50))
    {
        qDebug() << "No GBR file!" << endl;
        file.close();
        exit(1);
    }

    if (version != 2)
    {
        qDebug() << "Unknown GBR version!" << endl;
        file.close();
        exit(1);
    }

    // read the brush name
    unsigned int nameLength = headerSize-28;
    char* brushName_c       = new char[nameLength];
    in.readBytes(brushName_c, nameLength);
    brushName = QString(brushName_c);

    // read the image data
    unsigned int dataLength = width*height*colorDepth;
    data = new char[dataLength];
    in.readBytes(data, dataLength);

    // close file
    file.close();

    // generate thumbnail
    bool success = true;
    QImage::Format imageFormat;

    if (colorDepth == 1) {
        imageFormat = QImage::Format_RGB32;
    } else {
        imageFormat = QImage::Format_ARGB32;
    }

    QImage thumbnail(width, height, imageFormat);

    quint32 k = headerSize;

    if (colorDepth == 1 && data)
    {
        // Grayscale
        for (quint32 y = 0; y < height; y++)
        {
            for (quint32 x = 0; x < width; x++, k++)
            {
                qint32 val = 255 - static_cast<uchar>(data[k]);
                thumbnail.setPixel(x, y, qRgb(val, val, val));
            }
        }
    }
    else if (colorDepth == 4 && data) {
        // RGBA
        for (quint32 y = 0; y < height; y++) {
            for (quint32 x = 0; x < width; x++, k += 4) {
                thumbnail.setPixel(x, y, qRgba(data[k],
                                               data[k+1],
                                               data[k+2],
                                               data[k+3]));
            }
        }
    }
    else
    {
        success = false;
    }

    if (!success || !thumbnail.save(QString("thumbnail.png")))
    {
        qDebug() << "Failed saving the thumbnail..." << endl;
        success = false;
    }

    // debugging
    qDebug() << "headerSize" << headerSize << endl;
    qDebug() << "version"    << version << endl;
    qDebug() << "width"      << width << endl;
    qDebug() << "height"     << height << endl;
    qDebug() << "colorDepth" << colorDepth << endl;
    qDebug() << "spacing"    << spacing << endl;
    qDebug() << "brushName"  << brushName << endl;
    qDebug() << "image data" << (data ? "yes" : "no") << endl;


    // cleanup
    delete brushName_c;
    delete data;

    return 0;
}